MEMS based actuators are enabling the emergence of a host of new fiber-optic components that are more compact and reliable than their predecessors. They can also operate at lower power and are more cost effective. Examples of such components include switches, variable optical attenuators (VOA), tunable filters, optical channel monitors, wavelength selective switches, and wavelength blockers.
One particular class of MEMS devices for such applications is a two-axis MEMS Micromirror. In the simplest case, it is a two-axis gimbaled mirror driven by four quadrant electrodes, in parallel plate configuration, under the mirror. An improvement was made on this by Fernandez (U.S. Pat. No. 6,717,325) by using three independent electrodes (reducing the number of electrodes from 4 to 3). Further improvements were made through the use of comb drive actuation instead of parallel plate, such as Novotony (U.S. Pat. No. 6,914,710), Xiaoyu (U.S. Pat. No. 7,833,430), and Gritters (U.S. Pat. No. 7,872,394).
Notwithstanding these advantages, there remain some important limitations in the approaches of Novotony, Xiaoyu, Gritters and others. The two-axis MEMS Micromirror allows the body of the mirror portion to rotate in three dimensions using a design having an inner axis of rotation that is orthogonal to an outer axis of rotation. Some of the limitations of the two-axis MEMS Micromirror include poor performance under shock and vibration. Specifically, in dual-axis mirrors the reliability of the mirror's rotation and performance are affected by shock and vibration.
A novel design is presented here and offers improvement in the fabrication process of a dual-axis MEMS Micromirror, as well as distinct advantages in the actuation performance, reliability, and functional capabilities of the device. The novel design and performance enhancements of such devices are especially vital for applications demanding lower voltage and higher stability. There exist a need for a reliable MEMS Micromirror and ease of fabrication of such devices. The design and fabrication method proposed in this disclosure achieve these needs based on the use of a Double SOI wafer, which leads to a simplified fabrication process.